1. Field of the Invention
The invention relates to a boot for use in Alpine skiing of a type which is generally well known and which comprises a rigid shell base having a sole and on which an upper composed of a cuff and a rear spoiler is journalled to pivot around a transverse horizontal axis.
2. Description of Prior Art
The general orientation of the upper is measured for purposes of simplicity with reference to "the axis of the upper"; the upper axis normally being inclined frontwardly with respect to the vertical. The upper is made integral with the shell base and is inclined at an angle designated the "advancement angle". At rest the advancement angle of the upper is designated as the "static" advancement angle. The upper pivots around the static or median position since the upper is journal mounted on the shell base. In general, the more advanced the skier, and thus the more the upper is flexed with respect to the shell base, the greater is the static (median) advancement angle which is desired. The advancement angle can be on the order of about 13.degree.-20.degree. and sometimes may even reach 25.degree. while for the average skier an angle of 8.degree.-15.degree. is generally considered to be optimum.
Furthermore, depending upon the particular type of skiing being performed and the state of the snow, the skier may demand greater or lesser flexibility in the journal of the upper on the shell base. Therefore, it would be useful to be able to vary the advancement angle of the upper depending on the conditions. Thus, a relatively high rigidity in the upper is preferred in competition skiing on hard snow or ice, while greater flexibility is required on powdered snow in order to better distribute the weight applied to the ski and to spare the muscles during descent as well as when attempting to reach the flat ski position.
The above considerations have resulted in more and more skiers requiring not only that their boots have an average or static advancement angle which corresponds, or can be made to correspond, to their personal needs, but also that their boots exhibit a rigidity in the journal of the upper on the shell base which increases as a function of the bias which they exert on the upper, which adds to the comfort and safety of the user.